The present invention relates to an original connection system between a main body, such as a platform, a buoy or a column, operable at sea, and a superstructure such as a deck carrying the equipment.
Generally, the platform, buoy or column is formed from at least one element having a general oblong shape, such as that of a cylinder whose height is greater than the diameter. For reasons of stability at sea, this cylinder is generally in a vertical position in operation. The weight of the main body may reach several thousands of tons.
The deck supports the equipment such as the flare, helideck, living quarters, manifolds, separators etc . . . ; its weight may reach some thousands of tons. Taking into account its equipment, the deck must remain in a horizontal position.
The deck is generally positioned in the following way:
The main body, constructed in a horizontal position, is placed in the vertical position by ballasting, and the deck, loaded on a barge, is brought above the main body which is then unballasted so as to allow engagement between the deck and the main body.
The above operation must be performed in a sheltered zone so as to limit the engagement stresses which would be prohibitive out at sea. This assumes then that the deck-main body assembly is towed in vertical position to the site. If required, changing the operation site is effected in the same manner.
Typical prior art constructions of the aforementioned type are disposed in, for example, French patent applications or certificate of addition numbers: 2 298 471, 2 359 248 and 2 384 902 and British Pat. No. 1 525 242.
More precisely, the present invention relates to a connection system between a main body and a superstructure, which may be used in a sea environment, with the connection system comprising means for moving said main body relatively to said superstructure and guide means cooperating with said moving means. The moving means may be inscribed on a cylindrical surface, with the moving and guide means being adapted to allow at least a swinging movement of the main body relatively to the superstructure.
With a main body formed by at least one element having an oblong shape, the connection system of the invention may comprise at least one guide element, such as a rail or a slide, whose form is inscribed substantially on a cylinder, with an axis of the cylinder being perpendicular to the axis defined by an elongation direction of the element with oblong shape of said main body. The guide element will be fixed rigidly to the main body, as well as moving means, such as rolling means or shoes cooperating with with the guide element, said moving means being fixed to the lower parts of said superstructure. In this case, it is not imperative for the axis of the above defined cylinder and the axis of the main body to be concurrent. Without departing from the spirit of the present invention, the guide element may be fixed to the superstructure and the moving means to the main body. The same is true when several guide elements are used, which may be distributed between the superstructure and the main body and of course the moving means will be distributed accordingly. The rolling means may comprise bodies equipped, if need be, with tires which may be inflatable. The moving means may comprise drive means driven by control means adapted to maintain the superstructure in a substantially fixed position in space, or to control movement thereof in space during swinging of the main body.
More particularly, in the case where the superstructure is a deck, the control means may be adapted to maintain the deck in a substantially horizontal position during the swinging operation of the main body.
A system of slings and hoisting gear or a rack and pinion system or equivalent means, such as hydraulic cylinders or jacks connecting the main body and the superstructure together may control the fixed position in space of said superstructure. Such a system may be controlled so as to hold the superstructure in a fixed position in space during the swinging operation of the main body.
Whether the system of the invention comprises drive means, or sling systems, or equivalent means, the operation for positioning or removing the same may comprise several steps, each comprising simultaneous swinging of the superstructure and of the main body through a limited angle and movement of the superstructure with respect to the main body. This movement may have an amplitude sufficient for compensating and/or anticipating at least partially the preceding limited angle swinging and/or following on this operation of moving the superstructure with respect to the main body.
In some variants, the connection system may comprise several guide elements whose shape is inscribed on the same straight axis cylinder, with each of these guide elements being situated in a plane perpendicular to the axis of the cylinder. In one advantageous embodiment, the connection system comprises three guide elements and the corresponding rolling means.
More particularly for reasons of convenience of construction, the guide elements may have a closed circular shape.
The connection system of the invention, when it is applied to a connection between a deck and a main body, presents a number of significant advantages.
More particularly, by virtue of the present invention, it is possible to form a temporary connection in a sheltered zone between the secondary installation in a horizontal position and the main body in a substantially horizontal position,
Additionally, it is possible to tow the deck-main body assembly in a substantially horizontal position to the operating site,
Moreover, with the present invention, it is possible to place the main body in a vertical position by ballasting, with the deck remaining in a horizontal position in all of the phases of ballasting of the main body,
The present invention also provides the possibility of permanently locking the deck to the main body, and, the reversibility of each operation, allows a change in the operating site.